1. Field of the Invention
The present invention relates to a golf club.
2. Description of the Related Art
Recently, a face and a body of a golf club head are made thin in order for example, to increase a size of the head so as to enlarge a sweet spot and enhance a repulsive force of the head so as to improve a carry. Accordingly, a material having high-strength and high-hardness has come into use for this thinning purpose. In a golf club having a head made of a high-strength and high-hardness material, since a sound generated by hitting a golf ball is too high, the sound is not only harsh, but there have been concerns about a harmful effect on ears of a player, etc.
As a technique for solving those problems, for instance, Japanese Unexamined Patent Publication No. 6-39061 discloses a head which comprises a metallic face and a head body, both defining a hollow interior of the head, wherein the hollow interior is filled with a filler material such as non-metallic plastic, a thermoplastic material, an elastomeric material or a material with metallic particles or metal spheres added as a filler thereto.
Moreover, as a technique of providing a non-metallic material for a head, Japanese Unexamined Patent Publication No. 9-322952 discloses an iron head having a recess portion on its rear side, wherein an organic material having a preset Young's modulus of from 1 to 10000 MPa is provided on the recess portion; an intimate contact area between an inner surface of the recess portion and the organic material is arranged to be more than or equal to 10 cm2; the organic material is, for instance, a vulcanized gum such as butadiene rubber, natural rubber, SBR, thermosetting resin such as urethane resin and epoxy resin, and thermoplastic resin such as polyethylene, polystyrene, polyamide, and polyvinyl chloride.
The above described conventional techniques are aimed at obtaining a comfortable sound when hitting a golf ball by using an organic material such as plastic, thermoplastic material, elastomeric material, vulcanized gum or the like. Those materials, however, are too soft when having rich elasticity, while they have only poor elasticity when having rich hardness. Accordingly, there is a problem that combining elasticity and hardness is difficult.